View of the exterior between piers 15 (left) and 17 (right) in the Embarcadero in San Francisco, Calif., on Thursday, March 26, 2009. The Exploratorium is moving from the Palace of Fine Arts to piers 15 and 17.

Photo: Hardy Wilson, The Chronicle

View of the exterior between piers 15 (left) and 17 (right) in the...

Image 3 of 4

An artist rendering shows what a hypothetical outdoor Exploratorium "exhibit" might look like at Pier 15.

Photo: EHDD Architecture

An artist rendering shows what a hypothetical outdoor Exploratorium...

Image 4 of 4

An artist rendering shows what the Exploratorium might look like inside a section of Pier 15 in San Francisco.

In what would be the biggest change to San Francisco's waterfront since the construction of AT&T Park, the city's renowned Exploratorium science museum is close to clearing important milestones in its push to construct a new home at Piers 15-17.

The museum long ago outgrew the Palace of Fine Arts space where it started in 1969, but despite huge popularity with families and educators, it has struggled to relocate for more than a decade.

Things seem to have changed this time around.

A draft environmental review for the latest proposal failed to find any major problems, and a final report could be complete by the end of June. Museum officials are working on a lease with the Port of San Francisco. Even the notoriously strict agencies that govern what can be built along a waterfront are unofficially endorsing the project, which could be done as early as 2012 if it is approved by port officials and the Board of Supervisors.

"This would be a wonderful jewel on the waterfront and will serve our mission by giving us the space to do what we are famous for," said Exploratorium spokeswoman Linda Dackman.

The new Exploratorium would relocate the hands-on science center to an area that attracts droves of visitors and is easily reached by BART, Muni and ferries. Annual attendance is expected to soar from 600,000 to 800,000.

Long time coming

Under a proposal that has been in the works since 2004, the museum would enter a 66-year lease with the Port of San Francisco for Pier 15 and refurbish it, and later expand to nearby Pier 17.

The new museum would triple its current space to 326,000 square feet and feature an observatory, indoor and outdoor exhibits, classrooms, theater, cafe and remake of the popular Tactile Dome, where visitors feel their way in total darkness through hundreds of shapes and materials. An area between the two piers currently paved with asphalt would be opened up to create a lagoon.

Parts of the Pier 15 and 17 buildings, which are part of a historic district, would be restored, and the badly deteriorated and seismically unstable piers would be repaired.

Dackman said that current space limitations force museum officials to turn away two-thirds of the teachers who apply for workshops and one-third of the schools seeking field trips.

Sarah Delaney, a middle school science teacher, said she greatly benefited from teacher training organized by the Exploratorium. Delaney said the size and location of the proposed museum would allow it to serve a broader diversity of students.

"The fact that it will be located on the Embarcadero will make it accessible to a much bigger population. Students from the Bayview and Oakland will be able to get there a lot more easily."

The ambitious project has a long way to go, however, and the Exploratorium has been stumbled before.

Several potential venues failed to pan out in recent years, including an office complex at Francisco and Montgomery streets near Fisherman's Wharf, a building at Seventh and Townsend streets, and Pier 70.

The latest project is expected to cost about $175 million, but it's unclear how close the museum is to meeting that goal. Dackman declined to discuss funding because a lease had not yet been signed.

In documents presented to a Board of Supervisors committee in 2006, museum officials estimated that they would attempt to raise $120 million for the new museum and that donors had pledged $88 million of that.

The museum also would receive approximately $835,000 annually in port rent credits in exchange for completing pier repairs, according to port project manager Jennifer Sobol.

While museums without marine themes are not specifically listed as acceptable waterfront uses under state law, officials at the State Lands Commission, which governs what can be built along the California waterfront, say talks with the museum are moving forward.

Public access to waterfront

The museum "would be a real opportunity for public access to the waterfront," said Paul Thayer, the commission's executive officer. "The public doesn't have much of an opportunity to see the water because it is often obstructed by piers."

The project also requires a full environmental review, which is nearly complete.

A draft of the review raised concerns about the impact of construction on nesting Western gulls, and marine mammals, such as seals, which could be affected by sound waves caused by driving piles into the bay sediment to support piers.

Yet such problems could be addressed, according to the report. Pier building roofs could be netted to prevent gulls from nesting there, or construction could be suspended during nesting months.

Measures also could be employed to reduce pile-driving sound waves. Examples include using wood piles and creating an air barrier between the pile and the surrounding water.

"We think it's a wonderful use for the waterfront," said Sobol, who along with other port staff hopes to present a lease agreement with the museum to the port commission by fall. "We started really rejuvenating the waterfront with the Ferry Building and the ballpark, and this would be a continuation of that."